1. Field of the Invention
This invention relates generally to water filter or treatment systems, and, more specifically, to systems including intermediate storage for filtered or treated water.
2. Related Art
Conventional filter systems permit water to flow in a single pass through filter or treatment media to a storage tank, water tap, or other usage device. When additional filtering of stored water is desired to move contamination or biocides immediately before use, conventional systems typically require multiple filter canisters and complicated valving and piping.
Reid (U.S. Pat. No. 5,248,417) discloses a double-flow-through system using a single filter housing. In this system, water flows through a single bed of filter media and then through a combination outlet-inlet port to a storage tank. When a tap or faucet is opened, the stored water flows back through the combination port into the filter housing to flow again through the filter media bed and then out to the tap. Thus, the Reid ""417 system provides two passes through a single bed of filter media, with intermediate storage between the two passes.
The Reid ""417 apparatus includes a pair of check valves to control flow to and from the combination port, and, thus, to and from storage. When the water tap is closed, unfiltered water enters the upper portion of the filter housing through the inlet port and is prevented by a cup-type check valve from flowing directly to the combination outlet-inlet port. The water passes a first time through the media and flows up through a filter tube to the combination port. A slit-type check valve disposed at the top of the filter tube prevents water from flowing from the combination port back into the filter tube. Once the water tap is opened, the cup-style check valve allows water to flow from storage through the combination port, through the cup check valve into the top portion of the filter housing, through the media a second time, and then to the tap.
Reid (U.S. Pat. No. 5,232,590) discloses a water filtration apparatus with an internal by-pass for conducting water from a water source to a storage tank without passing through the filter media. When the tap or faucet is opened, water then flows back from the storage tank into the filter housing, through the filter media, out the outlet port, and out of the faucet.
Grayson, et al. (U.S. Pat. No. 5,082,557) discloses a filter control head for directing water to various locations. The control head can direct water to a first filter canister, to a drain, and to a storage tank. When a downstream usage device demands water, purified water may then flow from the storage tank, back to the control head, and then to a separate, second filter canister and a downstream usage device.
An object of the present invention is to provide an economical system with at least two stages of filtration or treatment and with intermediate storage. The invention features a xe2x80x9csplit-flowxe2x80x9d scheme in which inter-stage liquid is split off to intermediate storage and then subsequently returned to a later stage of processing, preferably in the same filter housing, combined with liquid flowing through the first stage of processing. Another object of the invention is to provide an apparatus wherein the first and second filtration/treatment zones are both contained in a single filter housing. Another object of the invention is to provide a system having two or more filtration zones that each may be operated at different flowrates.
The present invention comprises a filter housing comprising first and second filtering zones in series, and removal means and return means for conducting liquid to and from storage in between the zones. Separate, intermediate outlet and inlet ports may extend through the housing wall, or, preferably, a single, intermediate combined outlet-inlet port may accommodate flow in both the outward (to storage) and the inward (from storage) directions.
In a preferred embodiment, the intermediate outlet and inlet ports is combined into a single port, which is in fluid communication with an elongated filter tube extending through the first zone. The bottom of the filter tube is located near the bottom of the first zone and near the top of the second zone. Therefore, the filter tube collects water after passage through the first zone and allows it to flow out of the intermediate port to storage. Upon opening of a tap, which is in fluid communication with the outlet of the second zone, the stored water flows back into the intermediate port and into the filter tube, out of the bottom of the filter tube, through the second zone, and through an outlet port to the water tap.
Each of the multiple zones of the present invention may include one or more beds or layers comprising filter media, treatment media, or void space. In a preferred embodiment, the first zone comprises both anti-bacterial treatment with an iodinated resin and extended contact between bacteria and the iodide/iodine species in a void chamber. In this preferred embodiment, the intermediate storage provides additional contact time between biocide and bacteria, and the second zone filters the water and removes the biocide from the water immediately before use. The structural configurations of the zones may be designed for either axial flow, radial flow, or both types of flow distribution.